Marine Le Pen's call for a ban on headscarves, Jewish kippas, and even the djellaba in public is not some new low in the long and abject story of France's failure to come to terms with itself. We have been here before, and unfortunately we will be again. That is the tragedy of modern France, a tragedy that entered a new absurdist phase the day Marine Le Pen recast herself as the protector of the values of the Republic.

You need to suffer from a very particular kind of historical amnesia not to find banning the kippa in France grotesque, particularly as Le Pen used it to kickstart her party conference just as Holocaust survivors were gathering at Drancy to remember the 60,000 Jews who were deported to the death camps from there by French police. The blocks in which they were held now house mostly north African immigrants and their children and grandchildren, some of whom wear headscarves and, on very rare occasions, djellabas.

It was them that Le Pen had in mind when she threw in the kippa to appease her party's hardcore antisemites horrified by her courting of Jewish groups in the runup to last May's presidential elections, in which she took one in five of the votes.

Marine Le Pen is not her father, who described the Final Solution as "a detail of history"; she is a far more dangerous animal, with an acute sense of what irks the French – much like the Daily Mail has for the English. As the new, "reasonable" face of the Front National, who last year declared herself a "life-long Zionist", she claims she has no problem with the kippa, yet she knows that a certain rump France – including those on the left most attached to its republican principles – does.

If you apply the logic of a strictly secular state, Le Pen insists, you cannot discriminate against one without discriminating against all – egalité also means "equality of discrimination". So if the Muslims are to be prevented from challenging the Republic by wearing headscarves or other "religious symbols" in the streets, so must the Jews.

Of course, it is never going to happen – no more so than the CRS being sent out to hunt down bonnes soeurs on the streets of Paris, not even if the appalling Jean-François Copé, the architect of the burqa ban (which in the name of liberté effectively condemned women who wear the niqab to a kind of house arrest), becomes leader of Sarkozy's old UMP.

But it does create the toxic atmosphere the Front thrives in and which France thought it had left behind with Sarkozy, who drove the country half mad with fear and prejudice attempting to cling to power, yet still lost. When France voted for François Hollande, it was as much voting for sanity as for the Socialist.

Now, with growing signs of irritation with Hollande – itself a kind of psychic hangover from the omnipresence of Sarkozy as president – and the centre-right riven by a leadership battle, there is a danger again of Le Pen filling the vacuum with her xenophobic juju.

Only the Front can defend the secular values of the Republic, she claims. Which raises the question, what kind of republic needs the protection of Marine Le Pen? The truth is that a secular fundamentalism as moronic and short-sighted as the obscurantist Islam that it purports to oppose has long deformed the founding principles of the French Republic. You need only look at this week's Charlie Hebdo for the proof.

The Republic – the most beautiful of all the great ideas France has given the world – was meant to be about tolerance, liberty, fraternity and equality. But it has come to mean the opposite, making France unhappy, unequal and almost permanently febrile. The battle to hold the line on an outdated, untenable vision of that republic has become a Verdun of suspicion, prejudice and anger. And, like Verdun, if some way is not found out of the quagmire, France will be sapped for generations to come.